The　number　of　rules　in　belief　rule　base(BRB)　may　induce　the　problem　of　combinatorial　explosion.　However,　most　previous　works　on　rule　reduction　are　based　on　feature　extraction,　whose　effectiveness　depends　on　the　expert　knowledge.　Therefore,　an　objective　method　based　on　rough　set　theory　is　proposed,　which　does　not　depends　on　any　knowledge　in　addition　to　belief　rule　base.　The　method　of　rule　reduction　analyzes　each　belief　rule　according　to　equivalence　class　division　thought,　and　then　eliminates　the　redundancy　of　referential　values.　Finally,　a　numerical　case　study　to　evaluate　armored　system　is　analyzed　and　compared　with　the　typical　subjective　method　in　the　number　of　reduced　rule　and　the　accuracy　of　decision-making.　The　results　show　that　the　proposed　method　is　feasible　and　effective,　and　superior　to　the　existing　subjective　method　of　rule　reduction.　©,　2014,　Northeast　University.　All　right　reserved.